/*-------------------------------------------------------------------------
 *
 * chklocale.c
 *        Functions for handling locale-related info
 *
 *
 * Copyright (c) 1996-2017, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *      src/port/chklocale.c
 *
 *-------------------------------------------------------------------------
 */

#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

#ifdef HAVE_LANGINFO_H
#include <langinfo.h>
#endif

#include "mb/pg_wchar.h"


/*
 * This table needs to recognize all the CODESET spellings for supported
 * backend encodings, as well as frontend-only encodings where possible
 * (the latter case is currently only needed for initdb to recognize
 * error situations).  On Windows, we rely on entries for codepage
 * numbers (CPnnn).
 *
 * Note that we search the table with pg_strcasecmp(), so variant
 * capitalizations don't need their own entries.
 */
struct encoding_match
{
    enum pg_enc pg_enc_code;
    const char *system_enc_name;
};

static const struct encoding_match encoding_match_list[] = {
    {PG_EUC_JP, "EUC-JP"},
    {PG_EUC_JP, "eucJP"},
    {PG_EUC_JP, "IBM-eucJP"},
    {PG_EUC_JP, "sdeckanji"},
    {PG_EUC_JP, "CP20932"},

    {PG_EUC_CN, "EUC-CN"},
    {PG_EUC_CN, "eucCN"},
    {PG_EUC_CN, "IBM-eucCN"},
    {PG_EUC_CN, "GB2312"},
    {PG_EUC_CN, "dechanzi"},
    {PG_EUC_CN, "CP20936"},

    {PG_EUC_KR, "EUC-KR"},
    {PG_EUC_KR, "eucKR"},
    {PG_EUC_KR, "IBM-eucKR"},
    {PG_EUC_KR, "deckorean"},
    {PG_EUC_KR, "5601"},
    {PG_EUC_KR, "CP51949"},

    {PG_EUC_TW, "EUC-TW"},
    {PG_EUC_TW, "eucTW"},
    {PG_EUC_TW, "IBM-eucTW"},
    {PG_EUC_TW, "cns11643"},
    /* No codepage for EUC-TW ? */

    {PG_UTF8, "UTF-8"},
    {PG_UTF8, "utf8"},
    {PG_UTF8, "CP65001"},

    {PG_LATIN1, "ISO-8859-1"},
    {PG_LATIN1, "ISO8859-1"},
    {PG_LATIN1, "iso88591"},
    {PG_LATIN1, "CP28591"},

    {PG_LATIN2, "ISO-8859-2"},
    {PG_LATIN2, "ISO8859-2"},
    {PG_LATIN2, "iso88592"},
    {PG_LATIN2, "CP28592"},

    {PG_LATIN3, "ISO-8859-3"},
    {PG_LATIN3, "ISO8859-3"},
    {PG_LATIN3, "iso88593"},
    {PG_LATIN3, "CP28593"},

    {PG_LATIN4, "ISO-8859-4"},
    {PG_LATIN4, "ISO8859-4"},
    {PG_LATIN4, "iso88594"},
    {PG_LATIN4, "CP28594"},

    {PG_LATIN5, "ISO-8859-9"},
    {PG_LATIN5, "ISO8859-9"},
    {PG_LATIN5, "iso88599"},
    {PG_LATIN5, "CP28599"},

    {PG_LATIN6, "ISO-8859-10"},
    {PG_LATIN6, "ISO8859-10"},
    {PG_LATIN6, "iso885910"},

    {PG_LATIN7, "ISO-8859-13"},
    {PG_LATIN7, "ISO8859-13"},
    {PG_LATIN7, "iso885913"},

    {PG_LATIN8, "ISO-8859-14"},
    {PG_LATIN8, "ISO8859-14"},
    {PG_LATIN8, "iso885914"},

    {PG_LATIN9, "ISO-8859-15"},
    {PG_LATIN9, "ISO8859-15"},
    {PG_LATIN9, "iso885915"},
    {PG_LATIN9, "CP28605"},

    {PG_LATIN10, "ISO-8859-16"},
    {PG_LATIN10, "ISO8859-16"},
    {PG_LATIN10, "iso885916"},

    {PG_KOI8R, "KOI8-R"},
    {PG_KOI8R, "CP20866"},

    {PG_KOI8U, "KOI8-U"},
    {PG_KOI8U, "CP21866"},

    {PG_WIN866, "CP866"},
    {PG_WIN874, "CP874"},
    {PG_WIN1250, "CP1250"},
    {PG_WIN1251, "CP1251"},
    {PG_WIN1251, "ansi-1251"},
    {PG_WIN1252, "CP1252"},
    {PG_WIN1253, "CP1253"},
    {PG_WIN1254, "CP1254"},
    {PG_WIN1255, "CP1255"},
    {PG_WIN1256, "CP1256"},
    {PG_WIN1257, "CP1257"},
    {PG_WIN1258, "CP1258"},

    {PG_ISO_8859_5, "ISO-8859-5"},
    {PG_ISO_8859_5, "ISO8859-5"},
    {PG_ISO_8859_5, "iso88595"},
    {PG_ISO_8859_5, "CP28595"},

    {PG_ISO_8859_6, "ISO-8859-6"},
    {PG_ISO_8859_6, "ISO8859-6"},
    {PG_ISO_8859_6, "iso88596"},
    {PG_ISO_8859_6, "CP28596"},

    {PG_ISO_8859_7, "ISO-8859-7"},
    {PG_ISO_8859_7, "ISO8859-7"},
    {PG_ISO_8859_7, "iso88597"},
    {PG_ISO_8859_7, "CP28597"},

    {PG_ISO_8859_8, "ISO-8859-8"},
    {PG_ISO_8859_8, "ISO8859-8"},
    {PG_ISO_8859_8, "iso88598"},
    {PG_ISO_8859_8, "CP28598"},

    {PG_SJIS, "SJIS"},
    {PG_SJIS, "PCK"},
    {PG_SJIS, "CP932"},
    {PG_SJIS, "SHIFT_JIS"},

    {PG_BIG5, "BIG5"},
    {PG_BIG5, "BIG5HKSCS"},
    {PG_BIG5, "Big5-HKSCS"},
    {PG_BIG5, "CP950"},

    {PG_GBK, "GBK"},
    {PG_GBK, "CP936"},

    {PG_UHC, "UHC"},
    {PG_UHC, "CP949"},

    {PG_JOHAB, "JOHAB"},
    {PG_JOHAB, "CP1361"},

    {PG_GB18030, "GB18030"},
    {PG_GB18030, "CP54936"},

    {PG_SHIFT_JIS_2004, "SJIS_2004"},

    {PG_SQL_ASCII, "US-ASCII"},

    {PG_SQL_ASCII, NULL}        /* end marker */
};

#ifdef WIN32
/*
 * On Windows, use CP<code page number> instead of the nl_langinfo() result
 *
 * Visual Studio 2012 expanded the set of valid LC_CTYPE values, so have its
 * locale machinery determine the code page.  See comments at IsoLocaleName().
 * For other compilers, follow the locale's predictable format.
 *
 * Visual Studio 2015 should still be able to do the same, but the declaration
 * of lc_codepage is missing in _locale_t, causing this code compilation to
 * fail, hence this falls back instead on GetLocaleInfoEx. VS 2015 may be an
 * exception and post-VS2015 versions should be able to handle properly the
 * codepage number using _create_locale(). So, instead of the same logic as
 * VS 2012 and VS 2013, this routine uses GetLocaleInfoEx to parse short
 * locale names like "de-DE", "fr-FR", etc. If those cannot be parsed correctly
 * process falls back to the pre-VS-2010 manual parsing done with
 * using <Language>_<Country>.<CodePage> as a base.
 *
 * Returns a malloc()'d string for the caller to free.
 */
static char *
win32_langinfo(const char *ctype)
{// #lizard forgives
    char       *r = NULL;

#if (_MSC_VER >= 1700) && (_MSC_VER < 1900)
    _locale_t    loct = NULL;

    loct = _create_locale(LC_CTYPE, ctype);
    if (loct != NULL)
    {
        r = malloc(16);            /* excess */
        if (r != NULL)
            sprintf(r, "CP%u", loct->locinfo->lc_codepage);
        _free_locale(loct);
    }
#else
    char       *codepage;

#if (_MSC_VER >= 1900)
    uint32        cp;
    WCHAR        wctype[LOCALE_NAME_MAX_LENGTH];

    memset(wctype, 0, sizeof(wctype));
    MultiByteToWideChar(CP_ACP, 0, ctype, -1, wctype, LOCALE_NAME_MAX_LENGTH);

    if (GetLocaleInfoEx(wctype,
                        LOCALE_IDEFAULTANSICODEPAGE | LOCALE_RETURN_NUMBER,
                        (LPWSTR) &cp, sizeof(cp) / sizeof(WCHAR)) > 0)
    {
        r = malloc(16);            /* excess */
        if (r != NULL)
            sprintf(r, "CP%u", cp);
    }
    else
#endif
    {
        /*
         * Locale format on Win32 is <Language>_<Country>.<CodePage> . For
         * example, English_United States.1252.
         */
        codepage = strrchr(ctype, '.');
        if (codepage != NULL)
        {
            int            ln;

            codepage++;
            ln = strlen(codepage);
            r = malloc(ln + 3);
            if (r != NULL)
                sprintf(r, "CP%s", codepage);
        }

    }
#endif

    return r;
}

#ifndef FRONTEND
/*
 * Given a Windows code page identifier, find the corresponding PostgreSQL
 * encoding.  Issue a warning and return -1 if none found.
 */
int
pg_codepage_to_encoding(UINT cp)
{
    char        sys[16];
    int            i;

    sprintf(sys, "CP%u", cp);

    /* Check the table */
    for (i = 0; encoding_match_list[i].system_enc_name; i++)
        if (pg_strcasecmp(sys, encoding_match_list[i].system_enc_name) == 0)
            return encoding_match_list[i].pg_enc_code;

    ereport(WARNING,
            (errmsg("could not determine encoding for codeset \"%s\"", sys)));

    return -1;
}
#endif
#endif                            /* WIN32 */

#if (defined(HAVE_LANGINFO_H) && defined(CODESET)) || defined(WIN32)

/*
 * Given a setting for LC_CTYPE, return the Postgres ID of the associated
 * encoding, if we can determine it.  Return -1 if we can't determine it.
 *
 * Pass in NULL to get the encoding for the current locale setting.
 * Pass "" to get the encoding selected by the server's environment.
 *
 * If the result is PG_SQL_ASCII, callers should treat it as being compatible
 * with any desired encoding.
 *
 * If running in the backend and write_message is false, this function must
 * cope with the possibility that elog() and palloc() are not yet usable.
 */
int
pg_get_encoding_from_locale(const char *ctype, bool write_message)
{// #lizard forgives
    char       *sys;
    int            i;

    /* Get the CODESET property, and also LC_CTYPE if not passed in */
    if (ctype)
    {
        char       *save;
        char       *name;

        /* If locale is C or POSIX, we can allow all encodings */
        if (pg_strcasecmp(ctype, "C") == 0 ||
            pg_strcasecmp(ctype, "POSIX") == 0)
            return PG_SQL_ASCII;

        save = setlocale(LC_CTYPE, NULL);
        if (!save)
            return -1;            /* setlocale() broken? */
        /* must copy result, or it might change after setlocale */
        save = strdup(save);
        if (!save)
            return -1;            /* out of memory; unlikely */

        name = setlocale(LC_CTYPE, ctype);
        if (!name)
        {
            free(save);
            return -1;            /* bogus ctype passed in? */
        }

#ifndef WIN32
        sys = nl_langinfo(CODESET);
        if (sys)
            sys = strdup(sys);
#else
        sys = win32_langinfo(name);
#endif

        setlocale(LC_CTYPE, save);
        free(save);
    }
    else
    {
        /* much easier... */
        ctype = setlocale(LC_CTYPE, NULL);
        if (!ctype)
            return -1;            /* setlocale() broken? */

        /* If locale is C or POSIX, we can allow all encodings */
        if (pg_strcasecmp(ctype, "C") == 0 ||
            pg_strcasecmp(ctype, "POSIX") == 0)
            return PG_SQL_ASCII;

#ifndef WIN32
        sys = nl_langinfo(CODESET);
        if (sys)
            sys = strdup(sys);
#else
        sys = win32_langinfo(ctype);
#endif
    }

    if (!sys)
        return -1;                /* out of memory; unlikely */

    /* Check the table */
    for (i = 0; encoding_match_list[i].system_enc_name; i++)
    {
        if (pg_strcasecmp(sys, encoding_match_list[i].system_enc_name) == 0)
        {
            free(sys);
            return encoding_match_list[i].pg_enc_code;
        }
    }

    /* Special-case kluges for particular platforms go here */

#ifdef __darwin__

    /*
     * Current macOS has many locales that report an empty string for CODESET,
     * but they all seem to actually use UTF-8.
     */
    if (strlen(sys) == 0)
    {
        free(sys);
        return PG_UTF8;
    }
#endif

    /*
     * We print a warning if we got a CODESET string but couldn't recognize
     * it.  This means we need another entry in the table.
     */
    if (write_message)
    {
#ifdef FRONTEND
        fprintf(stderr, _("could not determine encoding for locale \"%s\": codeset is \"%s\""),
                ctype, sys);
        /* keep newline separate so there's only one translatable string */
        fputc('\n', stderr);
#else
        ereport(WARNING,
                (errmsg("could not determine encoding for locale \"%s\": codeset is \"%s\"",
                        ctype, sys)));
#endif
    }

    free(sys);
    return -1;
}
#else                            /* (HAVE_LANGINFO_H && CODESET) || WIN32 */

/*
 * stub if no multi-language platform support
 *
 * Note: we could return -1 here, but that would have the effect of
 * forcing users to specify an encoding to initdb on such platforms.
 * It seems better to silently default to SQL_ASCII.
 */
int
pg_get_encoding_from_locale(const char *ctype, bool write_message)
{
    return PG_SQL_ASCII;
}

#endif                            /* (HAVE_LANGINFO_H && CODESET) || WIN32 */
